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Abstract: TH-PO153

Long-Term Effects of Hypercalcemia in Kidney Transplant Recipients with Persistent Hyperparathyroidism

Session Information

Category: Bone and Mineral Metabolism

  • 502 Bone and Mineral Metabolism: Clinical

Authors

  • Cojuc, Gabriel, Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran, Ciudad de Mexico, Ciudad de México, Mexico
  • Marino-Vazquez, Lluvia A., Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran, Ciudad de Mexico, Ciudad de México, Mexico
  • Pichardo, Nathalie D., Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran, Ciudad de Mexico, Ciudad de México, Mexico
  • Cruz Rivera, Cristino, Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran, Ciudad de Mexico, Ciudad de México, Mexico
  • Reza-Albarrán, Alfredo A., Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran, Ciudad de Mexico, Ciudad de México, Mexico
  • Correa-Rotter, Ricardo, Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran, Ciudad de Mexico, Ciudad de México, Mexico
  • Morales-Buenrostro, Luis E., Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran, Ciudad de Mexico, Ciudad de México, Mexico
  • Ramirez-Sandoval, Juan Carlos, Instituto Nacional de Ciencias Medicas y Nutricion Salvador Zubiran, Ciudad de Mexico, Ciudad de México, Mexico
Background

Hypercalcemia is prevalent in kidney transplant recipients (KTRs) with hyperparathyroidism. However, its long-term impact on graft function is uncertain.

Methods

Prospective cohort study investigating adverse graft outcomes associated with persistent hypercalcemia (free calcium >5.2 mg/dL in ≥80% of measures) and inappropriately elevated PTH (>30 pg/mL) in KTRs. Asymptomatic mild hypercalcemia was observed unless complications developed.

Results

We included 385 KTRs. During a 4-year (IQR 1-8.2) median follow-up, 62% of KTRs presented persistent hypercalcemia. Compared to KTRs without hypercalcemia, there were no significant differences in graft dysfunction (10% Vs. 12%,p=0.61), symptomatic urolithiasis (5% Vs. 3%, p=0.43), biopsy-proven calcium deposits (6% Vs. 5%, p=1.0), fractures (6% Vs. 4%, p=0.64), and a composite outcome of urolithiasis, calcium deposits, fractures, and parathyroidectomy indication (10% Vs. 5%, p=0.55) in subjects with persistent hypercalcemia. In a subset of 76 KTRs, those with persistent hypercalcemia had higher urinary calcium (median 84 [43-170] Vs. 38 [24-64] mg/day,p=0.03) and iFGF23 (median 36 [24-54] Vs. 27 [19-40] pg/mL,p=0.04) levels, and lower 25D levels (11.3±1.2 Vs. 16.3±1.4 ng/mL,p<0.001). An iPTH level <300 pg/mL was associated with a reduced risk of post-transplant hypercalcemia in a multivariate analysis (OR 0.51, 95% CI 0.32-0.80).

Conclusion

Long-term persistent mild hypercalcemia, with inappropriately elevated iPTH, was frequent in KTRs after transplantation. This condition closely resembled a mild form of primary hyperparathyroidism, with hypophosphatemia and hypovitaminosis D as well as increased urinary calcium and iFGF23 levels. Despite these symptoms, the risk of adverse graft outcomes was low.

Outcomes associated with hypercalcemia